Longwall mining machine having automatic means to maintain angular setting



Aug. 20, 1968 F. SMALL ET AL LONGWALL MINING MACHINE HAVING AUTOMATIC MEANS TO MAINTAIN ANGULAR SETTING 5 Sheets-Sheet 1 Filed Sept. 16, 1966 INVENTOR L LO/ A MD M W E 0 R A H m R Aug. 20, 1968 SMALL ET AL 3,397,915

LONGWALL MINING MACHINE HAVING AUTOMATIC MEANS TO MAINTAIN ANGULAR SETTING Filed Sept. 16, i966 5 Sheets-Sheet 2 70 o '-F IG. 8.

27 F/G. 4. M

F IG. 2" 70 F 1 o 30 FIG. 6.-

INVENTORS FRED SMALL RicHARD WARD BY Aug. 20, 1968 SMALL ET AL 3,397,915

LCNGWALL MINING MACHINE HAVING AUTOMATIC MEANS TO MAINTAIN ANGULAR SETTING Filed Sept. 16, 1966 5 Sheets-Sheet 5 INVENTORS FRED SMALL RICHARD WARD BY United States Patent 3,397,915 LONGWALL MINING MACHINE HAVING AUTOMATIC MEANS TO MAINTAIN AN- GULAR SETTING Fred Small, Ormskirk, and Richard Ward, Worsley, England, assignors to Gullick Limited, Wigan, Lancashire, England, a British company Filed Sept. 16, 1966, Ser. No. 580,063 Claims priority, application Great Britain, Oct. 6, 1965, 42,374/65; Dec. 8, 1965, 51,991/65 Claims. (Cl. 299-1) ABSTRACT OF THE DISCLOSURE Guide mechanism for guiding a mineral-mining machine with respect to the mineral seam is provided with supports which are controlled by inclination sensitive devices to position the guide mechanism in some predetermined plane relative to the mine floor and to retain the guide mechanism parallel to such plane when the guide mechanism is bodily displaced laterally after a cutting operation to prepare for the next cutting operation.

This invention is for improvements in or relating to apparatus for automatically levelling -or restoring a machine or article to a predetermined angular setting.

One praticular application of the present invention is to the mining industry.

In longwall mining it is usual to remove the coal or other mineral along a face of perhaps 100 to 300 yards in length. The coal seams are often inclined in the direction of the face advance and even these inclined seams may be subject to rolls, i.e. undulations in the coal seam. The coal cutting or like machine must, of course, follow the inclination and undulations in the seam. As a result the floor, which is formed by the coal cutting operation, may well be inclined or undulating.

The conveyor and line of roof supports behind it are advanced over this floor towards the face as getting of the coal proceeds. In one arrangement, following a cut of the coal face the conveyor is pushed over towards the face by means of hydraulic rams incorporated in hydraulically extensible roof supports after which, using the conveyor as an anchorage, the rams are retracted so as to advance the supports. Such supports are now Well known and are generally referred to as self-advancing supports.

It will be appreciated that if the conveyor is pushed over onto newly exposed floor which is inclined with respect to the floor on which the conveyor was previously standing, then the conveyor will be tilted out of its previous position of alignment with the seam. This is undesirable particularly as the coal cutting machine or the like is frequently mounted on and guided by the conveyor in its movement along the face.

Heretofore aligning of the conveyor with the seam, when it is pushed onto a newly exposed floor area, has been effected by wedges placed under the conveyor at strategic positions. Alternatively short stroke hydraulic jacks or the like have been used, such jacks being placed along the length of the conveyor and set to a predetermined extension.

The just-described arrangements are open to the objection that the human element is involved in continually setting and re-setting the conveyor in accordance with any inclination or undulation of the strata and erroneous setting may well occur. Furthermore, the coal 'ice under the conveyor may consist largely of fines which results in an impression of packing of the conveyor and give a false indication as to its angular disposition.

One object of the present invention is to provide an arrangement for automatically aligning the conveyor or setting it in a predetermined angular position whatever changes of gradient or undulation it should meet in its advance towards the coal face.

According to the present invention there is provided apparatus for levelling or restoring a machine or article to a predetermined angular setting comprising a pressurefluid-operated device having a part adapted to engage an abutment (e.g. a floor) and in combination therewith determine the angular setting of the machine or article, valve means controlling the supply of pressure-fluid to said pressure-fluid-operated device and an inclination sensitive device mounted or adapted to be mounted on the machine or article and operative to adjust said valve means. The inclination sensitive device may, for example, comprise a pendulum.

Conveniently, Where the apparatus is intended to level or set a machine or article at a predetermined angle with respect to a floor or the like one element (e.g. a piston) of the pressure-fiuid-operated device is in the form of a leg or foot for the machine or article, the elfective length of the leg or foot being adjusted by pressure-fluid under the control of the valve means so as to achieve the desired result.

The valve means controlling the supply of pressurefluid to the pressure-fluid-operated device may be electrically operated, the pendulum or other inclination sensitive device adjusting or actuating an electrical control component connected in the electric circuit of said valve means.

In one preferred arrangement of this nature the pendulum or other inclination sensitive device adjusts a potentiometer forming one element in a differential potentiometer network. This differential potentiometer network is associated with an electronic differential amplifier. The output of the amplifier is applied to a differential relay which controls the electrically-operated valve means controlling the supply of pressure-fluid to the pressure-fluidoperated device. Thus, the latter is appropriately actuated to level or restore a conveyor or other article to its predetermined angular setting.

Embodiments of the invention will now be described, by way of example, as applied to an automatic levelling arrangement for a coal face conveyor. It should be understood that similar arrangements can be applied to machines or articles other than conveyors. In the following description reference is made to the accompanying drawings in which:

FIGURE 1 is a sectional elevation of one embodiment,

FIGURE 2 is a fragmentary sectional elevation of the embodiment according to FIGURE 1 showing the valve means positioned to effect a levelling operation of the conveyor,

FIGURES 3, 4 and S are diagrams which will be referred to in describing the mode of operation,

FIGURE 6 shows diagrammatically a modified arrangement in which a potentiometer network, differential amplifier and differential relay control an electrically operated valve means of the pressure-fluid-operated device.

FIGURE 7 shows a pendulum-operated inclination sensitive potentiometer used in the embodiment according to FIGURE 6,

FIGURE 8 shows a diiferential relay contact arrangement, used in the embodiment according to FIGURE 6,

3 and the manner in which the differential relay is connected to the valve means,

FIGURE 9 shows diagrammatically as application of the invention to the bedplate of a coal cutting machine so that automatic control of the direction of machine advance is obtained. In other words, the cutting machine is kept automatically at a predetermined angle of alignment with the seam irrespective of any longitudinal and/or transverse tilting of the conveyor on which it rides, and

FIGURE 10 is a diagrammatic plan view of a pendulum-operated valve utilized in the embodiment of the invention shown in FIGURE 9.

Referring to FIGURES 1 to of the drawings, C indicates a Panzer coal face conveyor having at spaced intervals along its front edge (i.e. the edge remote from the coal face), a series of hydraulically operated automatic levelling devices in accordance with the invention.

Each levelling device 10 comprises a hydraulic cylinder 11 in which works a piston 12 having a piston rod 13 which terminates in a foot or pad 14. The foot or pad 14 normally extends below the bottom race 15 of the conveyor.

The cylinder 11 has ports 16 and 17 for the inlet and exhaust of pressure-fluid. The inlet and exhaust of pressure-fluid through the ports 16 and 17 is controlled by a slide valve 18 having pressure-fluid inlet ports 19 and an exhaust port 20. A pipe 19a connects the ports 19 to a source of hydraulic pressure. The valve 18 is shown diagrammatically and in practice it may be preferable to use a balanced piston valve or some other form of valve.

Adjustment of the slide valve 18, relatively to the ports 16 and 17, is effected by a pendulum device comprising a bellcrank lever 21 pivoted at 23 to a bracket 23a on the cylinder 11 and having one of its limbs connected by a universal joint 22 to the slide valve 18.

The other limb of the bellcrank lever 21 has an arcuate slot 24. A pendulum weight 25 is suspended freely from the pivot 23 and is provided with a clamping screw or the like 26, which passes through the slot 24, by which it can be clamped to the bellcrank lever so that said lever and the pendulum weight become rigid one with the other.

Assuming that it is required to maintain the conveyor C horizontal, then the clamping screw 26 is set mid-way in the slot 24 so that the limb of the bellcrank lever connected to the slide valve 18 and the pendulum weight are at right-angles to one another.

FIGURE 3 shows the conveyor on a floor area F which is horizontal.

FIGURE 4 shows the conveyor pushed over, following at cut of the coal face, onto a floor area F which is inclined downwardly towards the face. This tilt of the conveyor is objectionable and is corrected automatically as follows:

Immediately the conveyor is pushed into the position shown in FIGURE 4, the pendulum device 25 acts, due to its natural inclination to remain perpendicular, on the slide valve 18 and moves it from the position shown in FIGURE 1 (the fully closed position) to the position shown in FIGURE 2. Fluid-pressure then flows via the ports 19 and 17 into the cylinder 11 so as to raise the piston 12 and in effect shorten the leg 13, 14 until the conveyor is brought to the desired horizontal condition as shown in FIGURE 5. \Vhen it reaches this condition the pendulum device will again -be in the position shown in FIGURE 1 and the slide valve 18 will be in the fully closed position.

When pressure-fluid is entering the cylinder 11, via the ports 19 and 17, below the piston 12, it is exhausted from above the piston via the ports 16 and 20.

It will be understood that if the inclination onto which the conveyor has been pushed had been inclined downwardly away from the coal face, then the slide valve 18 would have been moved so as to supply pressure-fluid to the upper part of the cylinder 11, via the ports 19 and 16, and allow pressure-fluid to exhaust from the lower part of the cylinder via the ports 17 and 20, the leg thus being extended in length until the conveyor is brought to the horizontal.

.In some cases, of course, it may be required that the conveyor or some other machine or article is desired to maintain automatically an inclined disposition. This can be brought about with the device above described by setting the clamping screw 26 and thereby the pendulum 25 nearer to one end of the slot 24 than to the other.

The modified arrangement shown in FIGURES 6, 7 and .8 comprises a potentiometer network including a pendulum operated potentiometer 27, a reference potentiometer 28 and an initial balance potentiometer 29.

The differential current from this network, resulting from movement of the pendulum 30 (see FIGURE 7) of the potentiometer 27, is amplified by the transistorised differential amplifier 31 and fed to the differential relay 32. The latter is connected in circuit with solenoid valves 33 and 34 at shown in FIGURE 8.

The general construction of the apparatus including that of the pressure-fluid-operated levelling devices proper may be similar to that described above with reference to FIGURES 1 to 5 of the drawings. The valve arrangement 16, 17, 18 and 19 being replaced by the solenoid valves 33 and 34.

In the arrangement shown in FIGURE 6 the input to one side of the amplifier 14 is pre-set by means of the [manually adjustable potentiometer 28 and the input to the other side is taken from the wiper of the pendulumactuated-potentiometer 27.

Assuming that is is desired to maintain the conveyor or other machine level, then, with said conveyor or other machine set level the potentiometer 27 will be positioned by its associated pendulum 30 in its mid-position and the reference potentiometer 28 is set in its mid-position. The initial balance potentiometer 29 is then adjusted so that the currents in the two coils 32a and 32b of the differential relay 32 exactly balance each other so that neither contact, of the relay, is closed and the solenoids of the valves 33 and 34 are open circuited.

If the pendulum 30 is displaced due to tilting of the conveyor or other machine, the differential amplifier 31 becomes unbalanced and one or other of the contacts in the differential relay 32 is closed. As a result, one of the solenoid valves, 33 or 34, is operated and pressure-fluid is supplied to a hydraulic jack or other pressure-fluidoperated levelling device such as is shown at 12, 13, 14 in FIGURE 1. The latter is thereby extended or retracted, according to which of the valves 33 or 34 has been operated, to bring the conveyor or other machine back to its initial level setting. When this has been done the pendulum 30 will have returned to its mid-position, re-balanced the amplifier and caused the contacts in the differential relay 32 to open. The solenoid valve 33 or 34, whichever has been operated, then closes so as to shut off the supply of pressure-fluid to the jack.

The balance point of the system need not necessarily be the mid-point of the pendulum-actuated potentiometer 27 as the reference potentiometer 28 can be set to give an initial displacement. In this way, the conveyor or other machine can be given an initial tilt which is then maintained automatically.

Means may be provided for damping the pendulum and adjusting the rate of flow of pressure-fluid to the jacks or other pressure-fluid-operated devices so that there is little or no over-shoot in the re-setting operation. Overshoot could cause objectionable oscillation in the system.

Referring now to FIGURES 9 and 10, the coal cutting machine, indicated diagrammatically at 35, has a cutter drum 36 and is situated on the conveyor C for movement therealong in the well known way. The base of the machine 35 has a single datum leg 37, of fixed length, and three adjustable legs 38, 39, 40 each in the form of a double-acting hydraulic jack. The reference numerals 41, 42 and 43 indicate hydraulic pipe lines to the retract sides of the pistons of the rams 38, 39 and 40 and the reference numerals 44, 45 and 46 indicate hydraulic pipe lines to the extension sides of the pistons of said rams.

The leading end of the coal cutting machine is indicated by the reference numeral 47 and the trailing end by the reference numeral 48.

FIGURE shows a simplified pendulum-operated valve arrangement for controlling the three hydraulic jacks 38, 39 and 40. In FIGURE 10 the ports 41, 42, 43, 44, 45 and 46 correspond to the hydraulic pipe lines 41, 42, 43, 44, 45 and 46 of FIGURE 9. The valve shown in FIGURE 10 has a valve chest or pad 49, formed with annular cavities 50 and 51, and adapted to work over the ports 41 to 46 inclusive. The valve chest 49 is controlled by a pendulum, the arrangement being such that the valve chest slides horizontally across the ports 41 to 46 according to the direction of swing of the pendulum. When the pendulum is vertical the position of the cavities 50 and 51 in relation to the ports -41 to 46 is as shown in FIG- URE 10, i.e. all said ports are closed.

The annulus 50 corresponds to the port 19 in FIGURE 1 and is the hydraulic feed line, Whilst the annulus 51 corresponds to the port of FIGURE 1 and is the hydrauiic return line.

Assuming that, due to tilting of the conveyor C in the direction of its length, the rear or trailing end 48 of the coal cutting machine rises with respect to the leading or front end 47, the resultant inclination of the machine will, through the pendulum, cause the valve chest or pad to slide in the direction of the arrow X in FIGURE 10. This brings the annulus 50 over the ports 42 and 43, which serve as the pressurefluid feed ports for retracting the rams 39 and 40, and at the same time brings the annulus 51 over the ports 45 and 46 which serve as exhaust ports when the rams 39 and are being retracted. Thus, the machine will be re-aligned with the seam.

Should the trailing end 48 of the machine fall with respect to the leading end 47 then a similar operation will take place except that the pendulum will swing in the direction of the arrow Y and the ports and 46 will serve as feed ports for the rams 39 and 40 and the ports 42 and 43 will serve as exhaust ports. Thus, the rams 39 and 40 will be extended so as to re-align the machine with the seam.

Should the machine be tilted in a direction having a component towards or away from the mineral face the pendulum will swing, for example, so as to connect the ports 41 and 42 to the pressure-fluid feed annulus and the ports 44 and 45 to the pressure-fluid exhaust annulus 51 or vice versa according to the direction of tilt relative to the face. Thus, the rams 38 and 39 will be retracted or extended, as the case maybe, so as to re-align the machine with the seam.

It should be noted that the datum alforded by the leg 37 is constant (i.e. the leg is of fixed length) and that all movements of the hydraulic legs or jacks 38, 39 and 40 are relative to this fixed distance.

We claim:

1. In combination, a mineral face conveyor having guide means for guiding a mineral-mining machine longitudinally with respect to a mineral seam on a longwall mine face, pressure-fluid jack-legs on said conveyor at spaced intervals therealong for supporting the conveyor from a floor of a mine working over which said conveycg is advanced towards the mineral face, a valve for each jack-leg controlling the flow of pressure-fluid to and from said jack-leg, a control means for each of said valves including an inclination sensitive device associated with the conveyor so as to move automatically when there is a change in the angle of the floor over which the conveyor is advanced, with respect to the floor on which the conveyor had previously been resting, and an operative connecting means between each valve and its control means whereby any such movement of the inclination sensitive devices results in adjustment of the valves to charge or discharge the jack-legs and effect lengthening or shortening thereof to restore the conveyor to its original angular disposition.

2. The combination claimed in claim 1 wherein each inclination sensitive device is a pendulum.

3. The combination claimed in claim 1 wherein each valve is an electrically operated valve and each inclination sensitive device adjust a potentiometer forming one element in a differential potentiometer network associated with an electronic differential amplifier, the output of said amplifier being applied to a diiferential relay which controls the electrically operated valve.

4. The combination claimed in claim 1 wherein each valve is an electrically operated valve and the inclination sensitive device of the control means for said valve adjusts an electrical control component connected in the electric circuit of the valve.

5. The combination claimed in claim 1 wherein there is mounted to run on the conveyor a mineral-mining machine which itself also has pressure-fluid jack-legs which rest on the guide means of the conveyor, valve means controlling the flow of pressure-fluid to and from said jack-legs of the mineral-mining machine and control means for said valve means including an inclination sensitive means associated with the mining machine so as to move automatically and adjust said valve means and thus charge or discharge the jack-legs, to lengthen or shorten them, to restore the machine to a predetermined angular disposition should it depart therefrom.

6. In a longwall mining machine system of the type including an elongate guide means adapted to rest on a previously cut mine floor portion adjacent to the mineral face to be mined, a cutting machine supported by said gulde means for movement therealong to cut the mineral face and provide a new floor portion and a new mineral face, and means for laterally displacing said guide means onto the new floor portion preparatory to the next cutt1ng operation, the improvement comprising:

adjustable means for supporting said guide means at a predetermined angular setting while resting on the previously cut mine floor portion,

and control means connected to said adjustable means for automatically maintaining said predetermined angular setting of the guide means when it is displaced from the previously cut floor portion to rest upon the new floor portion. 7. In the system defined in claim 6 wherein said adustable means comprises a plurality of pressure-fluid ack-legs, and said control means comprises an inclination sensitive device associated with each jack-leg.

8. In the system as defined in claim 6 wherein said guide means is a conveyor for receiving the material mined.

9. In the system defined in claim 6 wherein said adjustable means comprises a plurality of pressure-fluid jack-legs, and said control means comprises an inclination sensitive device associated with each jack-leg, said control means also including a valve connected to each inclination sensitive device, and means for varying the responsive portion of each valve with respect to its inclination sensitive device.

10. A longwall mining machine system comprising, in combination,

an elongate guide disposed upon a previously cut mine floor portion alongside the mineral face to be mined,

means supporting said guide in elevated position in a predetermined plane relative to said floor portion and including extensible-retractable legs supporting one side of said guide,

a cutting machine supported on said guide for movement therealong to perform a cutting operation on the mineral 'face and provide a new mine floor portion and a new mineral face,

means for displacing said guide laterally to rest upon the new floor portion alongside the new mineral face,

and control means connected to said legs for positioning said guide in a plane parallel to said predetermined plane when resting upon said new floor portion.

References Cited UNITED STATES PATENTS Sloane 299-1 Adams 91419 X Mercier 91-419 X Curlett 13746 X Taylor 13745 X ERNEST R. PURSER, Primary Examiner. 

